Why is Stepmania 5 beta 4, so bad?

i cant even play songs without issues. the frame rate keeps dipping and there's so much note-warping and glitchyness
Stepmania 5 beta 3 > Stepmania 3.95 > Stepmania 4 > OsuMania > Stepmania 5 beta 4.

That's strange, everything since beta 3 has had practically the same performance for me.
What theme are you using?
Are you sure it's beta 4 that causes the problem and not some other part of your system? (try beta 3 from the github release page and see if it has the same problem)

Beta 3 is what I currently use now and it runs Great. I want to move to beta 4 because everyone else uses it but I just cant.

Are you running SM5 inside wine? That might be the source of your problem.
I looked through older posts and saw that you didn't have an internet connection to it, and had trouble installing the dependencies to build. Most linux distros have some way of downloading packages directly and then installing from the downloaded packages, so it should be possible to find the packages you need from the site for the distro you use, put them on a USB drive, take them to your linux machine, and tell the package manager to install from there.

lol no, im using Windows 7 now. (probably should of specified this in the post). i also have a working connection on my pc so theres no need for USB drives

Can you describe your problem, and your system, in more detail than that? Whatever it is, that isn't enough detail to fix anything.